This invention relates generally to an improved system for operating of an upper plate driver on a surface lapping machine. More particularly, it relates to a system for connecting a plurality of driver slots with a plurality of upper plate locks, so as to provide locking connection between a driver member and an upper plate is an engaging position, but permitting the upper plate to be raised out of contact with the driver slot for access to the workpieces being lapped within the machine.
In conventional surface lapping machines, workpieces are held in carriers between upper and lower plates for grinding, lapping action. Typically, a driver is provided having a plurality of driver slots extending in evenly spaced manner about the driver, which is generally at the end of a shaft connected to a power source. The upper plate defines a plurality of locks such as rollers which may slide into the slots as the upper plate closes into operating position, to be driven in the operation. The upper plate may also be raised out of contact with the driver in the open position.
Accordingly, there is a problem when an upper plate is being closed into the operating position of getting the proper alignment of the driver slots on the driver and the locks on the upper plate. Typically, in a conventional machine one must manually rotate the upper plate to align these members. Alternatively, one drops the upper plate and then starts the rotation of the driver, causing the locks to suddenly fall into slots. However, when this is done, a sudden shock is imparted to the machine as the upper plate suddenly begins rotating. This shock can damage the workpieces as well as the machine. Accordingly, poor maintenance and performance may result, plus breakage and other damage to the workpiece.
Japanese Patent No. 59-132755, issued Sept. 5, 1984, discloses an improved system for easily connecting the upper plate to the drive member, involving a plurality of driver slots which flare uniformly outwardly at their top along the circumference to their driver member to reduce the difficulty of causing the upper plate locks to find the engaged driver slots. A plurality of slot guides are formed taperingly and positioned adjacent the driver slots, to define the slots.
While such an improved system may avoid some of the problems noted above, when compared with standard prior art for plate driving systems, the system has another problem as follows: if the upper plate locks descend directly onto the center of the slot guides, they will be out of position on the slot guide relative to the slots. Accordingly, as the driver rotates, at the moment of grabbing of the upper plate into rotation with the driver, tremendous shock to the workpieces may result. If the upper plate locks are secured without tension springs, the locks will hit hard upon the slot guide top centers in descending, to cause the tremendous shock. This can stop operation of the upper plate by damaging it.
By the invention of this application, the above problems are advantageously solved, for improved performance of lapping machinery.